What is Atrial Septal Defect?

Atrial Septal Defect is a congenital condition associated with abnormal blood flow between the left atrium and the right atrium.
Before birth there is a large connection between right and left atria. During development of the fetus the connection gradually disappears. However, in some cases the opening persists and is known as an atrial septal defect.

You see turbulent blood flow across the tricuspid valve between the right atrium and the right ventricle (the diastolic murmur).
This is caused by blood flow from the left atrium into the right atrium through the atrial septal defect.
There is further turbulent flow into the pulmonary artery causing the systolic murmur.

Atrial Septal Defect Murmur

This is atrial septal defect heard at the pulmonic position.
Use the play button on the torso to listen.

Both the first and second heart sounds are split.
The second heart sound splitting is fixed at 80 milliseconds.

S1 is normal. S2 is louder than normal.
In fact, you are hearing only the accentuated pulmonic component of S2 due to heart failure on the left side.

A brief diamond shaped murmur will be heard in early systole and another brief diamond shaped murmur in early diastole.

Atrial Septal Defect Animation

Congenital Heart Disease - Cases & Recordings

A short course on heart sounds associated with congenital abnormalities is available using the button below.
This course covers atrial septal defect, coarctation of the aorta, patent ductus arteriosus, ventricular septal defect,
tetralogy of Fallot and Epstein's anomaly.